Cladding with powdered metal to form bimetallic products



May 7, 1963 CLADDING WITH POWDERED METAL TO FORM BIMETALLIC PRODUCTSFiled June 16, 1958 FIG R. M. NOETHLICH, JR, ETAL 7 Sheets-Sheet 1 INVEN TORS RICHARD M. NOETHLIGH, JR, & JOSEPH G. DUNLEAVY JOHN G. KURA ANDJOHN L GISSY wag 1.

May 7, 1963 R. M. NOETHLICH, JR., ETAL 3,088,195

CLADDING WITH POWDERED METAL TO FORM BIMETALLIC PRODUCTS Filed June 16,1958 7 Sheets-Sheet 2 INVENTORS woman a. nosmuc JOSEPH e. DUNLEAV JOHNG. KURA m? .tL 1

May 7, 1963 R. M. NOETHLICH, JR. ETAL 3,088,195

CLADDING WITH POWDERED METAL TO FORM BIMETALLIG PRODUCTS Filed June 16,1958 T Sheets-Sheet 3 JMPAW M y 1963 R. M. NOETHLICH, JR. ETAL 3,088,195

CLADDING WITH POWDERED METAL TO FORM BIMETALLIC PRODUCTS Filed June 16,1958 T Sheets-Sheet 4 20 /490 M wErm/oq JOHW G A z/PAMHA/L'G/JJV 5% '7 WINVENTORS JOJEPH G W/VLEAV INVENTOE; emu/4P0 M NOE/'HA/CH,

7 Sheets-Sheet 5 ETAL R. M. NOETHLICH, JR,

CLADDING WITH POWDERED METAL TO FORM BIMETALLIC PRODUCTS J? JOSEPH a00mm v11 JOHN 6? 02/1 .woH/v L, was) By J W 9' 74;, L? a??? Fig 18 May7, 1963 Filed June 958 May 7, 1963 R. M. NOETHLICZH, JR, ETAL 3,083,195

CLADDING WITH POWDERED METAL TO FORM BIMETALLIC PRODUCTS Filed June 16,1958 7 Sheets-Sheet 6 f 3% W R) NLAW v; w {WW4 Maw w? i m 3 2 W. m. k 5a 0 Z W W.

May 7, 1963 R. M. NOETHLICH, JR.. ETAL 3,

CLADDING WITH POWDERED METAL TO FORM BIMETALLIC PRODUCTS Filed June 16,1958 7 Sheets-Sheet 7 INVENTORS. Haw/1P0 M NOE/'HL my, a? JOSEPH aDUNLEA W, H n Jowazum Howie/6s? ZWAM United States Patent 3,088,195CLADDING WITH POWDERED METAL TO FORM BIMETALLIC PRODUCIS Richard M.Noethlich, Jr., Joseph G. Dunleavy, and John G. Kura, all of Columbus,and John L. Gissy, Dublin, Ohio, assignors, by mesne assignments, toCopper-weld Steel Company, Pittsburgh, Pa., a corporation ofPennsylvania Filed June 16, 1958, Ser. No. 773,125 17 Claims. (Cl.29182.3)

This invention relates to the use of powdered metal in the cladding ofhigher strength or lower corrosion-resistant metal cores to formbimetallic members. More particularly, this invention pertains to anovel system for continuously producing bimetallic rods, wires andshapes having a ferrous core and clad to a controlled cladding thicknesswith a conductive and/or corrosion-resistant metal, initially inpowdered form, like aluminum, copper, or their respective alloys.

Elongated bimetallic members such as aluminum-clad and copper-clad wiresand rods are extensively used in industry and by utilities. Thus,Copperweld copperclad steel wires and rods are used for electricallyconductive wires for power, telephone and other communication or signalpurposes, for weather resistant fencing, for corrosion resistantconcrete reinforcement and for other electrical and mechanical uses.More recently, aluminum-clad wires with continuous ferrous cores thereinhave also been made and used in the mechanical and other fields. Suchprior practices have most commonly involved manufacture by theapplication of molten metal as a cladding material to the core metal, orthe use of preformed jackets subsequently welded or bonded to the core;or, as to relatively thin coatings, by hot dipping processes or certainkinds of electrodeposition.

However, it has not heretofore been possible, so far as we are aware, tomanufacture bimetallic clad core members by, e.g., using a ferrous rodor wire and aluminum or copper powdered metal respectively as therespective starting core and cladding materials and meet the desiredrequisites of adherence between cladding and core, of density andcontinuity of cladding, of bendability without physical or metallurgicaldamage to the composite member, and, further, of drawability when such acomposite member is to be further reduced in diameter by rolls orwire-drawing dies while maintaining a minimal ratio between thethickness of cladding metal and of core.

In a preferred practice of our invention, a powdered metal, e.g.,atomized powdered aluminum, is applied in a positive manner to a ferrouscore, roll compacted, heated, roll reduced in cross section and rollfinish rounded in a continuously moving metal line operation in the airat production speeds. Such preferred practice in the case of thealuminum cladding of steel rod provides direct metallurgical bondingbetween cladding and core metals uniformly around the core withoutformation of any continuous layer or more than traces of brittlealuminumiron compound. The cladding or coating of the bimetallic productso produced is a continuous, dense, nonporous, corrosion-resistantcover. The new product itself is quickly and economically producible andsatisfactory for a wide variety of electrical and mechanical servicesand uses including those hereinbefore mentioned.

Other objects and advantages of this invention will 3,088,195 PatentedMay 7,, 1963 be apparent from the following description and theaccompanying drawings, which are illustrative only, in which FIGURE 1 isa schematic view in side elevation of a continuous horizontal line forone practice of this invention to provide a bimetallic clad rod or wiresuitable, if desired, for further reduction in size by drawing;

FIGURE 2 is a view in side elevation, partly in section, of equipment inthe zone of FIGURE 1 at which powdered cladding metal is continuouslyapplied to a continu ous rod or wire core;

FIGURE 3 is a view in section taken along line III-III of FIGURE 2;

FIGURE 4 is a view, somewhat enlarged, taken along line lV-lV of FIGURE2;

FIGURE 5 sets forth one illustration of a means by which rolls such asthose shown in FIGURE 1 may be power driven;

FIGURE 6 is a schematic view in side elevation of an initially verticalcontinuous line for a practice of this invention;

FIGURE 7 is a depiction of a portion of a photomicrograph to illustratecontinuous bonding provided by this invention at an interface between aferrous core and a cladding metal like aluminum;

FIGURE 8, comprising portions 8A and 8B, is an overall view in sideelevation of a horizontal line for a preferred practice of thisinvention to provide, e.g., an alumi num clad ferrous rod or wire in acontinuous operation;

FIGURE 9 is a view in side elevation of the cladding powder applicatorand compacting roll stand taken along line IX-IX of FIGURE 14;

FIGURE 10 is a partial detail view, somewhat enlarged, illustrating onemode of providing lubricant and scraper means respectively for the backand front of a roll;

FIGURE I1 is a view taken along line XIXI of FIG- URE 10;

FIGURE 12 is a somewhat enlarged view partly in longitudinal crosssection of the applicator mechanism shown in FIGURE 9;

FIGURE 13 is an end view somewhat enlarged of the fin remover shown inFIGURE 9;

FIGURE 14 is a front view of the roll stand shown in FIGURE 9 with apart of the applicator mechanism removed for the purpose ofillustration;

FIGURE 15 is a view in side elevation of the hotreduction roll stand tofurther metallurgical bonding between cladding and core;

FIGURE 16 is a front view of the fin remover shown in FIGURE 15;

FIGURE 17 is a view in section taken along line XVIi -XVII of FIGURE 16;

FIGURE 18 is a rear view of the roll stand shown in FIGURE 15;

FIGURE 19 is a detail view somewhat enlarged showing the pass openingfrom the front formed by the rolls of the roll. stand of FIGURES l5 and18;

FIGURE 20 is a view in side elevation of the finish roll stand to roundthe clad rod and means to cool the cladding thereof; and

FIGURE 21 is a front view of the roll stand shown in FIGURE 20.

Referring to FIGURE-S 1 to 5, schematic means for practicing oneembodiment of this invention are shown in the form of a continuoushorizontal line of equipment on a plant floor to produce bimetallic cladwire or rod, which, for the sake of illustration, will be discussed inconnection with the production of a steel core aluminum-clad rod tosubsequently be cold drawn to wire size of lesser diameter. In suchequipment, a payout reel support may be provided for a reel 11 on whicha continuous length of ferrous rod 12 is wound. Rod 12 is maintainedunder tension as it passes through the line of equipment to a wind-upreel 14 on a wind-up reel support 15 which is at the end of the lineshown. It is not necessary in this invention to have the core rod 12coated with any flux, intermediate metal layer, or bond promotion agent.

Rod 12 may be passed through a straightener 16 and then may be cleaned,including any descaling that may be needed, in the illustrated line by acore cleaner 17, one form of which may be a mechanical grit-blaster suchas a Wheelabrator. In such a machine 17, any scale or oxide is removedfrom the surface of rod 12, and if grit is used, it is such as to cleanthe surface of the rod without burnishing it. If desired, gaseous orliquid bath cleaning means for rod 12 may be substituted. Cleaned core12 passes from machine 17 to a cladding applicator machine 18 and in sodoing may pass through a hood or mufile, if such is necessary to protectthe cleaned rod against the ambient atmosphere as when, e.g., the coreis readily oxidizable. Generally such a hood or mufile will not beneeded in view of the relative juxtaposition of machines 17 and 18.

Applicator 18 is used to apply powdered aluminum as the metal claddingto the cleaned steel core 12 in the illustrated embodiment of theinvention under immediate discussion. Preferably, when the claddingmetal is made from aluminum, it will be initially applied in the form ofatomized powder having a relatively low oxide content (less than 0.3% byweight) and a screen analysis in the to 200 mesh range, US. Standardsieve, with the major portion of such powder being of a size which isunder 40 and over 140 mesh (e.g., Alcoa No. 125 aluminum powder).Further, aluminum powder in other sizings (e.g., Reynolds No. 12120aluminum powder) and in other forms may also be used.

A hopper 19 in machine 18 may be used to contain such powdered aluminum,the powdered cladding metal 50 passing downwardly by gravity into thebottom of the hopper and from thence into a feed tube 20 extending inthe direction of movement of rod 12 as shown by the arrow 21. Rod 12passes axially through hopper 19 and feed tube 20 and is coaxial withthe forming tube end 22 of feed tube 20 and with a wholly closedcircular pass 23 in pressure rolls 24. A vibrator 25, such as a Syntron,may be affixed to hopper 19 to vibrate in a manner to assist in thecontinuous feeding of aluminum powder into feed tube 20 and from thenceevenly around core 12 in discharge end 22 immediately before core 12 andthe applied powdered metal for the cladding around it move into the biteof circular pass 23 formed by cooperating grooves 27 respectively infour pressure rolls in the set 24. Preferably, the pressure rolls 24 andsubsequent reduction rolls are power driven as shown, for example, byequipment such as illustrated in FIGURE 5 in connection with rolls 24.For convenience of reference, the clad rod leaving rolls 24 and passingthrough the balance of the line shown in FIGURE 1 for operations thereonis given the reference numeral 120, in which the core is 12 and thecladding is given the reference numeral 26.

In FIGURE 5, an electric motor 28 acts as a common power source. Motor28 is connected by a flexible coupling 29 to a shaft 30 on which one ofthe pressure rolls 24 is fixedly mounted. Shaft 30 may be provided witha bevel gear 31 and a spur gear 32 for respective connection to a bevelgear 33 and a driven spur gear 34. The gears 33 and 34 are keyed to stubshafts 35 and 36 to drive two of the remaining rolls 24 at identicalspeed.

Shaft 36 is also provided with a fixed bevel gear 37 which engages afurther bevel gear 38 on a stub shaft 39 to drive the remaining roll 24at the same speed and in the same direction, suitable bearings for allof the rolls being provided therefor in machine 18 in the line shown inFIGURE 1. Thereby, pressure rolls 24 not only density the cladding metalto an extent which may even slightly reduce the diameter of core 12somewhat, but they also move substantially at the speed of movement ofcore 12 which is under tension, thereby avoiding relative movementbetween the cladding 26 being pressed by them onto the core 12. Theadjoining mating edges 40 of the rolls 24 are preferably beveled to meetand inhibit the formation of longitudinal fins or fiash" on the outsidesurface of the clad rod 12a as it passes through pass 23 of the pressurerolls 24. As to such small amounts of fin formation as may occur incompacting rolls 24 and subsequent pressure rolls, provision fortrimming such fins off preferably should be made prior to the entry ofthe clad rod into any subsequent cross-sectional area reduction mill inthe continuous line.

The bimetallic rod 12a comprising core 12 and cladding 26 on thedelivery side of rolls 24 has adherency between core and cladding whichis less than that desired for the end use handling to which it will besubjected. Adhcrency among the cladding particles is promoted by heatingin a furnace 41 which is shown as having an electrical induction heatingcoil 42 therein. Leads 52 of coil 42 may be connected to a suitablesource and character of electric power for the induction heating serviceto be performed by the coil. Clad rod 12a passes through the center ofcoil 42, in the course of its continuous movement, at a suitable speed,the heater 41 being long enough to generate the desired temperature forthe desired period of time in the cladding metal 26 on clad rod 1211. Aclad rod like rod 12a moving at a speed of about feet per minute may becaused to reach a temperature of about 1100 F. by an induction heaterusing current having a frequency of about 20-00 to 3000 cycles persecond. It will be realized that in matters of this kind, somecompromise of temperature relative to time, and vice versa, may beeffected without departure from our invention. A controlled atmosphereof a generally non-oxidizing or somewhat reducing character may bemaintained in heater 41 and in any other location that may be utilizedin a practice of this invention where time, temperature, or other factorwarrant to inhibit oxide formation. The controlled atmosphere may be anitrogen-hydrogen mixture (e.g., up to 10% hydrogen with the balancenitrogen) or hydrogen or helium or other non-oxidizing gas.

Temperature equalization of clad rod 12a in heater 41 may be provided bya soaking section 43 before entering a rolling mill 44. Mill 44 may beprovided with a further set of power-driven pressure rolls 24apreferably having a modified round pass of lesser diameter than pass 23to effect a hot rolling reduction of the cross-section of rod 12a forbonding purposes, any single such hot rolling reduction preferably notbeing below about 10% of the clad rod cross-sectional area entering thepass of rolls 24a. At the exit of mill 44, the hot rolled clad rod 12ahas the aluminum cladding 26 directly bonded to the steel core 12, thecladding itself being practically non-porous, smooth and continuous suchthat when the clad rod is bent cold rather sharply, such cladding willneither crack nor break nor separate from the core. Dependent uponmetallurgical properties desired in the clad rod, a further temperaturetreatment of rod 12a exiting from mill 44 may take place in atemperature adjustment facility 45 before rod 12a enters mill 46 and asecond set of preferably power driven pressure rolls 24b to effect afurther reduction in the cross-sectional area of rod 12a in a maner toavoid causing relative wiping movement of cladding and core or anytendency to extrude the cladding relative to such core. Mufiles or hoods47 may be provided for clad rod between respective items of equipmentwhenever the use of a controlled atmosphere is indicated as hereinbeforeset forth.

Upon leaving mill 46, the rolled clad rod 12a is cooled in a coolingdevice 13 and may be passed into a cold rolling mill stand 48. Facility13 may have cooling tubes located therein or a cooling fluid may becirculated through its interior, such cooling fluid having a compositionwhich is non-reactive relative to clad rod 12a, to bring the temperatureof clad rod 12a down to a desired lower rolling temperature before therod enters mill 48. In mill 48, further sets of pressure rolls 24c,preferably power driven like the rolls 24, but with progressivelysmaller circular passes therethrough, are provided. It will berecognized by those to whom this invention is disclosed that theperipheral speed of respective sets of pressure rolls in a continuousline practice of this invention will be coordinated for such continuouspressure rolling action.

The order of reduction effected by each set of rolls 24c in theembodiment illustrated in FIGURE I preferably is about of the enteringcross-sectional area of the clad rod entering each such set of rolls24c, until the clad rod is of the desired diameter for the subsequentpurpose it is to serve. Such lower temperature rolling may be used toobtain suitable drawing characteristics of the rolled clad rod 12a forcertain product applications. Provision may be made for intermediateheating of the clad rod if needed to counteract any tendency toward alessened softness or ductility because of its being rolled or drawn.

A practice of this invention as described yields a metallurgical bondbetween the core metal 12 and the cladding metal 26 as schematicallyillustrated in FIGURE 7 where the interface 49 discloses the presence ofa coherent bond better than a mere mechanical bond, but yet one in whichthere is an absence of any significant quantity of brittle aluminum-ironcompound (in the case of aluminunrclad steel) and an absence ofdeleterious extensive diffusion causing brittle phase formation at suchinterface. The bond at interface 49 is adherent enough so that whenreduced clad rod 12a on reel 14 is cold drawn to wire size, it has beendiscovered that the radius of the core and that the radial thickness ofthe cladding thereon will both decrease while the cladding continues togenerally uniformly surround that core during such drawing. The finishedbimetallic article will therefore be in a form, in the illustratedpractice under discussion, of an aluminurnclad wire with a steel coresuitable for electric power, telephone, and signal and other electricaland mechanical uses.

A further practice of our invention is schematically illustrated in anequipment line shown in our FIGURE 6 of the drawings. Therein, partscorresponding generally in structure and in functioning to equipmentshown in FIGURES 1 to 5 are provided with the same reference numeralswith the addition of a prime factor thereto. In FIGURE 6, ametallurgically clean ferrous rod 12' is fed vertically downwardly inself-centering relation through a hopper 19' containing powdered metal50 to serve as a cladding metal for rod 12. Hopper 19' feeds powder 50'into forming tube 22' by gravity to uniformly and entirely surround rod12' as both enter the nip of the pressure rolls 24". The clad rod 12aimmediately upon leaving rolls 24' may be passed through an inductionheating coil 42' and through a hot-reduction rolling mill 44 to completethe densifying and bonding of the cladding to the rod core. A hood 41'may be provided around coil 42' and rolls 24, suitable openings 51 beingprovided in hood 41' for the circulation of a non-oxidizing controlledatmosphere within it. When clad rod 12a leaves coil 42', it is led inthe form of a catenary loop 53 through a pit 54 below plant floor 55',to enable the rod 12a to enter a horizontal line of equipment forreduction rolling. Thus, rod 12a engages a guide roller 56 of a largediameter as red 12a leaves pit 54 and enters a temperature adjustmentfacility 45' in a horizontal direction before passing through mill 46.After leaving mill 46', red 12a" may move through a mufiie 47 andthrough a second rolling mill 46a for a further reduction in thediameter of clad rod 12a". In leaving 46a, rod 12a may enter a coolingchamber 57 with a non-oxidizing controlled atmosphere therein, whichitself may be the cooling medium, to bring the temperature of clad rod12a" to a suitable temperature before it exits therefrom and is wound upon a windup reel 14'.

It will be recognized by those skilled in the art to whom this inventionis disclosed, that some variation in the order of steps of a newpractice of our invention as disclosed herein can be accommodated as inthe case of having a rolling reduction step prior to a heating step asdiscussed in connection with heaters 41 and 41; that heating may becaused to occur by means other than an induction heating coil; thatpowdered metal may be applied to a core by a positive feed or by havingmore than one machine like machine 18 in tandem, whether in vertical orin horizontal arrangement; that a heating step may be interposed betweenone or more of the reduction steps or of drawing dies; that the clad rodissuing from the last rolling mill may be led directly into a first setof drawing dies or elsewhere instead of being taken up on a reel likereel 14 or 14'.

The disclosure herein which has been described in connection with theproduction of a composite aluminumsteel rod or wire is also applicableto the production of such elongated bimetallic articles having copper asa cladding metal supplied initially against the core in the form ofpowdered copper pressed into intimate contact with every portion of thecore surface, as taught above. In the case of such copper-clad articlesproduced hereunder, the temperatures involved are higher, copper havinga higher melting point than aluminum. Thus, a rod with such coppercladding initially applied as pressed powder directly to a ferrous coremay be heated, in a furnace corresponding to furnace 41 or 41, up to atemperature of from about 1800" to about i900 F. in a non-oxidizingcontrolled atmosphere; and the hot rolling reduction steps in mills likemills 44 or 46 may take place at a temperature of from about 1600 toabout 1900 F. An annealing step at 1300 F. may be interposed followingany hot or cold rolling reduction step or die drawing step where theeventual service for the product indicates somewhat greater softness orductility may be desirable. Again, as in the case of thealuminum-ferrous bimetallic members produced by this invention,conditions are preselected such that the bond between the ferrous core.and copper cladding is a metallurgicai bond. In the case of copper, abond is obtained that is more than a mere mechanical bond with as apractical matter some diffusion of the respective metals into oneanother being permissible short of the formation of a deleterious zoneor layer, since no harmful brittle compound as such is formed at theinterface.

As an example, a steel rod of AISI Cl020 composition having a diameterof A of an inch was press-roll clad to a diameter of about 9.42 of aninch with Charles Hardy type A electrolytic powdered copper metal andthen heated up to 1900 F. in a hydrogen atmosphere. Thereupon, thetemperature of the clad rod was brought to about 1690" F. in a heliumatmosphere and reduced by hot rolling through pressure rolls to adiameter of 9.295 of an inch. The product was then drawn through severaldies to a final diameter of 0.096 of an inch to successfully provide acopper-clad steel wire of that diameter; an intermediate annealinghaving been performed on the wire being drawn at a temperature of 1300F. in a non-oxidizing controlled atmosphere (10% hydrogen H nitrogenhNwhen the diameter of the wire was 0.114 of an lIlC Comparably,aluminum-rich and copper-rich powdered metal mixtures and like metalsmay be applied to ferrous and other cores for the production ofelongated bimetallic members in which the core (whether in rod, wire orother form) may, if desired, be entirely surrounded by a cladding metalhaving a lesser tensile strength or greater corrosion resistance, orboth, than the core material, in a continuous or in a non-continuousoperation as may be desired, with the production of a bond between thecladding and core such that the articles so produced may serve suitablyin fields where bendability, elasticity, ductility and the otherproperties of such materials are desirable. Moreover, various generallynon-oxidizing atmospheres or atmospheres on the reducing side may beutilized in the above illustrated practices of this invention. And,while this invention has been described principally in the light of theproduction of clad rod and clad wire, it will be appreciated that ourinvention is applicable to the production of clad flat and cylindricalbase shapes irrespective of whether or not such cladding is applied soas to wholly enclose the cores or bases of such shapes. Moreover, theterm rod when used alone shall be deemed to include wire.

Preferred Embodiment A preferred embodiment of our invention isillustrated in the form of the continuous cladding line shown in FIG-URES 8 to 21, inclusive, for the production of a bimetallic product suchas aluminum clad steel rod in which the aluminum cladding ismetallurgically bonded to the ferrous core. As used herein, the term rodincludes material of rod and wire gauge sizes as well as material ofround or other cross-sectional shape. The metals discussed include onesof like properties including alloys of the metals named, respectively.In the product made by the preferred embodiment, the core is uniformlyclad and the cladding is very dense and virtually wholly free of voids;the cladding is continuous, is adherent to itself and to the core and isof relatively uniform thickness around the core. Such product isproducible by the preferred embodiment at commercial production rateswith a minimum of manpower and expense and fully meets practical andcommercial test, service and use requirements for such a product. Thethickness of the cladding further can be varied relative to the crosssection of the core within the capacity of the particular equipmentemployed to produce a given final size of clad rod.

In the general arrangement of the preferred line shown in FIGURE 8,there is a flipper-type payout reel having diametrically oppositelyextending arms 101 supporting an active coil 102 of ferrous rod beingutilized as the core material for the clad rod product then being madeand an at ready coil 103 on the other arm 101. A butt Welder 104 islocated adjacent one side of reel 100 and enables the trailing end 102aof coil 102 to be welded to the leading end 1030 of the ready coil 103as core rod 105 continues to be pulled from coil 102 into the mechanismshown in FIGURE 8. When the ends 102a and 103a are welded together, anyflash or offset at the weld joint is ground off or otherwise removed andthe weld may be annealed if desired in the welder itself as by a manualpost-weld anneal control. Core rod 105 is pulled in the direction of thearrow into a straightener 106 having a powered bank of pinch rolls 107and two further banks of straightening rolls 10-8 in two planes so thatthe rod issues from straightener 106 in a straight line which ismaintained through the apparatus as far as the capstan roll mechanism109.

A wheel thrown abrasive metal grit machine 110 mechanically cleans thecore rod to place it in a metallurgically clean state as it passesthrough machine 110 between entry guide roll 111 and exit guide roll112, and an elevator 113 returns grit above a selected size to a supplyhopper 114, finer particles and dirt being removed and depositedoutside. The core 105 issuing from machine 110 has an unsmooth somewhatrough lit texture surface free of foreign matter including carbonaceoussmut. Other methods of descaling and cleaning, including wire brushing,may be utilized instead.

The metallurgically clean core rod is then pulled through an applicatormechanism 115 where the green cladding metal, such as atomized (e.g.,Alcoa No. 125) aluminum powder, is fed by positive means into apredetermined diameter around the core rod immediately prior to itsentry into a roll compacting mill 116. One suitable aluminum powder forthe illustrated equipment would have a particle distribution as follows.

U.S. Standard Sieve:

Mesh- Percent retained On 20 About 1 max. On 40 About 10 max. On 70 30to 50. On 140 35 to 55. On 200 About 10 max. Through 200 About 0.5 max.

A cladding powder bin 117 is provided adjacent the applicator mechanismand periodically replenished. A vibratory feeder 118 is connected to thebottom of bin 117 and operated to maintain a reservoir of such claddingpowder in a hopper 119 at the top of applicator mechanism 115. Avibrator 120 may be attached to the front wall of hopper 119 tofacilitate the passage of cladding powder into a positive powderapplicator 121.

Applicator 121 is fixed in brackets 122 rigidly secured to a mainbracket 123 and to the face plate 124 of compacting mill 116. Bracket123 is also secured to plate 124. A hollow arbor 125 in applicator 121is drilled for the axial passage therethrough of core rod 105. A helicalscrew 126 is secured to the exterior of arbor 125 to force claddingpowder uniformly around the surface of core rod 105 as it enters thebite of the closed circular roll pass defined by four Turks-head rolls127 in mill 116. In going through such pass, the powder cladding on rod105 is compacted forming a green clad rod 105a in its green or compactedform. The pressure in the pass of mill 116 is preferably sufficient todensify the cladding powder and possibly slightly reduce the diameter ofthe ferrous core by a few thousandths of an inch. The compacting by mill116 will produce a density in the cladding powder which is greater than98% of the density of high-purity wrought aluminum. Longitudinal finsformed at the parting line of the mating edges 165 of the power-drivenrolls 127 are milled off by a fin remover 128 as the compacted clad rod105a leaves the mill rolls of stand 116.

The metal work line along which the green clad rod 105a passes continuesthrough an induction heater machine 129, entry guide rolls 130 and exitguide rolls 131 being mounted on the front and back of the inductionheater stand supporting an induction heater coil 132 in concentricrelation to the work or pass line. In the induction heater, the rod 105ais very quickly heated through the cladding and interface between thecore and cladding to a temperature not less than 900 F., or higher, andmoves on directly into a hot reduction mill 133. In mill 133, a furtherset of powered Turks-head rolls 134 are provided with a further whollyclosed pass which bond cladding and core, reduce the clad rod andslightly flatten each quadrantal portion of the surface engaged cthereby. The power-driven rolls 134, like the powerdriven rolls 127, arerotated at a speed so as to exert no drag or force tending to shift thecladding relative to the core of the clad rod going through therespective pass thereof and, indeed, such power-driven rolls maysomewhat aid the movement of the clad rod through such respective pass.A fin remover 135 shaves the slight longitudinal fins produced at thecorners in the pass through the rolls in the parting planes defined bythe engaging mating edges In moving through the pass of mill 133, thehot compacted clad rod 105a has the aluminum cladding and ferrous corebrought into more intimate contact and achieves a metallurgical bondbetween the aluminum and steel without the production of any continuousinterface layer of aluminum-iron compound or any substantial formationof that compound. Such traces of compound as may appear are notdetrimental. In mill 133, the cross-sectional area of the clad rod isreduced preferably not less than to a maximum of about 25%, both thealuminum cladding and ferrous core sharing in such reduction.

The bonded clad rod leaving [in remover 135 goes to a finish sizingrolling mill 136 having unpowered rolls 137 therein preferably rotated45 around the axis of the rod line relative to the position of the rollsin mills 116 and 133. Thereby, the bottom of the grooves in the rolls137 encounter the definned corners of the bonded clad rod leaving mill133 and provide a final flattening of those corners and a finishrounding of the surface of the clad rod. Substantially no reduction ismade by the roll pass in mill 136. The rod 105 and clad rod 105:: do notappear to twist appreciably in passing through the respective millswhich preferably are placed closely together thereby economizing inspace. As the round bonded clad rod leaves mill 136, it is still quitehot and a cooling water spray mechanism 138 is used to reduce thetemperature of the cladding thereon at least to a temperature above theboiling point of water, preferably about 250 to 300 F., when water issuch coolant so that the rod is dry by the time that it makes its firstwrap around the far wheel of capstan 109.

Capstan 109 is provided with a drive wheel 139 and a driven wheel 140.The drive wheel 139 is powered by an adjustable speed drive 141. Thefinished clad rod from mill 136 first engages the rear side of wheel 140and then engages the forward half of wheel 139 and then the rear side ofwheel 140 again in the desired numbers of wraps before passing on to acoiler mechanism 142. Such wraps around the capstan wheels 139 and 140provide the desired tension in the work line, avoid slippage and causewheel 140 to turn. The surfaces of the capstan rolls 139 and 14!] may begrooved if desired for loop separation, guidance and traction. The speedof the cap stan is synchronized as will be understood by those to whomthis invention is disclosed with the speed of the power-driven rolls instraightener 106 and the mills 116 and 133. Tension supplied by thecapstan furnishes pulling force required to move the rod line in thedirection of the arrows shown in FIGURE 8 at the selected speed.

The finished clad rod 165a then passes from its last engagement withcapstan wheel 139 to a driven coiler 142 where the rod is engaged bypinch rolls 143 controlled by an adjustable screwdown 144. The clad rodthen passes between guide rolls 145 and beneath a deflector roll 146,the vertical height of which may be adjusted by a manual control 147 toplace a predetermined curvature in the steel core of the clad rod 105agenerally equal to the desired diameter of the coil. A laterallyextending mandrel 148 is provided and at the start of an operation thefree end of a rod is threaded between guide rolls 149 and passed betweena shear block 150 and a cylinder operated shear knife 151 which iselectrically or otherwise timed to sever the finished clad rod after thedesired number of coil loops have been made. The curvature in the cladrod produced by the deflector roll 146 is sufficient to keep the leadingend coiling around the mandrel 148 in a helical outwardly travelingmanner until the coil is severed by the shear as aforesaid, whereuponthe next coil begins to form, shoving the earlier coil or coilsoutwardly on the mandrel. If desired, the mandrel 148 may be powered soas to turn in a coiling direction as indicated by the arrow thereon.

FIGURES 9 to 14, inclusive, show the cladding mill 116 in greaterdetail, together with the applicator mechanism 115 and fin removed 128associated therewith. The front end of the arbor 125 is keyed to asprocket 152 which is rotated by an adjustable speed motor-reducer set153 connected to sprocket 152 by a chain 154 in a direction to cause thescrew thread 126 to feed cladding powder in a rearward direction towardthe tip of the applicator. Arbor is provided with a thrust collar 155keyed thereto which engages a bearing 156 secured in casing 121. Thrustroller bearings 157 rotatably support the entry end of the shaft ofarbor 125 which terminates at 158 where it is keyed to sprocket 152.

Cladding powder enters the interior of casing 121 through an opening 159in communication with the bottom of hopper 1 19, such powder filling thespace around helical screw blade 126 inside of the interior of casing121 forwardly of collar 155 and exteriorly of arbor 125. A relativelyshort, blunt, frusto-conical tip 160 having an axial passagetherethrough is fastened to the rear end of arbor 125. Tip 160 has atapering exterior surface generally parallel, or slightly divergent,relative to the interior surface of a nozzle member 161 secured to thefront of casing 121. The space between the exterior of tip 160 and theinterior of nozzle 161 does not constrict the crosssectional area of thecladding powder being forced through by rotation of the screw 126 at apredetermined speed relative to the speed of the moving rod 105. Nozzle161 is provided with a throat portion 162 between the discharge end oftip 160 and its own discharge end in which the cladding powder is firmlypressed by the applictaor uniformly and concentrically around the rod105 substantially just as such powder cladding and core rod enter thebite of the compacting circular closed pass 163 through the four-axisTurks-head rolls 127. By means of thin, tapered ribs 164 extendingrearwardly in the respective planes of the mating surfaces 165 betweenthe respective rolls 127 and in very close proximity thereto, the escapeof cladding powder from the bite of pass 163 into the nip betweenadjoining mating faces 165 moving toward engagement with one another isgreatly inhibited. Hence, formation of radially upstanding longitudinalfins at the intercardinal points around the circumference of the greencompacted clad rod 105a is materially reduced or prevented. The rearwardbracket 122 on plate 124 acts to center that end of applicator 121 inalignment with the axis of pass 163.

As the green clad rod enters the bite and pass of rolls 127, it iscompacted and the cladding densified at ambient temperature to form thecompacted stage of clad rod 105a prior to its entry into heater 132. TheT urks-head rolls 127 have mating edges or faces 165 which form diagonalparting planes along the four intercardinal points relative to the axisof the rod line and the planes of the respective rolls 127. The circularpass 163 is formed by the four quadrantal rolling grooves 166 in therolls 127. Each roll 127 is provided with an axle 167 rotatably mountedin a slide 168 in a rigid frame 169 secured to the transverse verticalplate 116a of compacting mill 116. The frame is also mounted on legs 170fixed thereto and in turn fixed to the base 171. Such frame 169 andtransverse plate 116a are provided with suitable cutout portions, frontand rear, for the projection there through as shown of front and backportions of the respective rolls 127. Rearwardly extending wind plates172 are respectively secured to the sides of plate 116a and base 171 tofurther rigidify the roll stand. One of the slides 168 is prepositionedand each of the other slides 168 is engaged by a threaded screwdown rod173 and manually movable by a wrench for the squared ends 174 in theillustrated embodiment, each screwdown having vernier scale 175 toprovide information as to the precise setting selected when the matingfaces 165 are brought together around the axis of the rod line alongwhich the work passes.

Roll stand 116 is driven by an adjustable speed motorreducer set 176through a coupling 177 and parallel drive shafts 178 and 179interconnected by gears 180 keyed to the respective shafts. Only thevertical plane rolls in 11 mill 116 are power driven, with thehorizontal plane rolls 127 being driven by friction received from therespective top and bottom plane rolls between the mating faces at theparting plane.

In FIGURES l and 11, respective lubrication and scraping means are shownfor a roll in cladding mill 116 as illustrative of such lubrication andscraping means applicable to each roll in that mill and to each of theTurks-head rolls in mills 133 and 136-. Thus, the surfaces of the rollparting plane faces 165 and of the roll grooves 166 are each lubricatedby a felt pad 181 held by a holder 182 pivotally supported at 183 to alug 184 on the face 124 of frame 169. A pressure adjustable spring 185engages the outer end of the holder 182 to cause the pad 181 to pressagainst the roll surface mentioned. In cladding mill 116 it has beenfound that a continuous film of stearic acid is a suitable lubricant,such lubricant being wiped on the rolls as a solution of stearic acidand a volatile solvent such as trichloroethylene which solventevaporates readily. In the case of rolls 134 and 137 respectively inmills 133 and 136, it has been found that motor oil is a suitablelubricant and all of the lubricants used may be fed to the pads by oilcups or drip devices, or otherwise. Other lubricants may be used andfunction in the base of aluminum cladding to prevent sticking or gallingof the cladding material relative to the roll surfaces. In addition,scraper blades 186 are attached to an angle holder 187 pivotally mountedin a lug 188 secured to the back of plate 116a. An adjustable spring 189presses the outer end of holder 187 to press blade 186 into contact witha mating face 165, there being one such scraper blade for each suchmating face of each roll to remove any aluminum fragments which mightotherwise tend to accumulate upon those parting surfaces.

A table 190 is secured to base 171 of mill 116 between the wings 172 tosupport the fin remover 128 fastened thereto. A rear end view of finremover 128 in somewhat larger detail is shown in FIGURE 13. Ascompacted clad rod 105a issues from the roll pass of mill 116, it islikely to have slight longitudinal and radially extending fins along thenortheast, southeast, southwest and northwest points considering northas a vertical line originating at and extending above the axis of themetal line along which rod 105a is passing. Such fin remover has a base191 for its milling cutters, a milling tool 192 for one pair 180 degreesapart of the four fins and a further milling tool 193 in differentlyoriented r juxtaposition thereto for the other pair of such fins. Themilling tools are mounted respectively on plates 194 at transverse 45and 135 degree slopes as seen in FIGURE 13. Each has a motor 195 coupledto a drive gear 196 which is in engagement with a driven gear 197. Bothgears are connected to shafts, the outer ends of which are respectivelyprovided with milling cutters 198 and 199 respectively. Such referencenumerals in FIGURE 13 are applied to subassembly 193 which is identicalto subassembly 192 at right angles thereto. The respective millingcutters rotate so as to engage the respective fins to be removed in adirection contrary to the direction of movement of the metal line, thespacing between the respective milling cutters being adjusted by thespacing of thrust bushing held in an end plate 200 to clear the regularperiphery of the compacted clad rod 105a while removing such fins at thebase thereof. Upon leaveing the fin milling cutters, the definnedcompacted clad rod is guided between a pair of steadying guide rolls 201se cured to a support 202 fixed to base 191.

A cladding thickness gauge may be provided on the discharge side of finremover 128 to continuously compare the thickness of the cladding atdifferent points around the periphery of the compacted clad rod. In thecase of aluminum cladding which is non-magnetic,

such would form a gap in a magnetic circuit including the steel core sothat a change in the thickness of such aluminum cladding would cause ameasurable change in the reluctance of such magnetic circuit. Suchmagnetic circuit would be connected to an indicating meter to show anyvariation from the selected cladding thickness as well as non-uniformityaround the periphery of the core.

As the definned compacted clad rod leaves mill 116 and fin remover 128,it passes directly to and through an induction heater mechanism 129,steadying guide rolls and 131 being mounted on standards 203 and 204 atthe respective ends of equipment 129. The induction heater 132 as showncomprises a straight envelope coil of copper tubing through which wateris circulated for cooling purposes. The tube is connected to a motorgenerator set 205 to supply sutficient alternating current power to theinduction heater coil at a frequency in the neighborhood of 2,000 to3,000 cycles per second, or higher. The alternating magnetic fieldgenerated induces currents within the compacted clad rod and hassufficient penetration to reach the interface between the cladding andthe core material resulting in rapid heating at the interface to atemperature kept below the melting point of the cladding material. Forpowdered aluminum cladding around a steel core, the preferred interfacetemperature is in the neighborhood of from 1000" F. to 1150 F. A broaderrange extends from about 900 F. up to a temperature not exceeding 1200F. The heated rod exiting from heater 132 radiates spectrum waves whichpass in timed sequence through the aperture in a rotating shutter 225and fall upon a thermistor bolomcter mechanism 226 interconnected to theelectrical circuit of heater 132 to vary the power input theretosufiiciently to maintain the temperature of rod 105:: leaving heater 132at a preselected operative level. The desired heating occurs in a matterof seconds. As will be understood by those having ordinary skill in theart to whom this invention is shown, some compromise is possible toachieve the selected temperature utilizing various electrical power,frequency and heater dimensions in correlation with the selected speed,size and character of the clad rod to be produced.

As the heated clad rod leaves the induction heater assembly 129, itpasses directly to the proximate hot reduction mill 133 shown in greaterdetail in FIGURES 15 and 18. That mill equipment has parts whichcorrespond generally in construction and function to parts of claddingmill 116 and such are marked with the same reference numerals with theaddition of a prime accent thereto. In hot reduction mill 133, the frame169 is secured to transverse support plate 133a (corresponding infunction to plate 116a) and the powered rolls 134 are again the top andbottom vertical plane rolls with the horizontal plane rolls 134 beingdriven by friction transmitted from the adjoining mating faces of thevertical plane rolls to the engaged mating faces of the horizontal planerolls respectively. Such mating faces are also shown in FIGURE 19.

Each of the hot reduction rolls 134 is provided with a roll pass groove206 of a different contour and size from that of the rolls 127 in thecompacting mill. Thus, in the closed pass 207 of the rolls 134, the areof each roll groove between the bounding parting planes defined by theengaged mating faces is slightly flattened in each quadrant controlledby a particular roll pass groove relative to the outline of a truecircular quadrant, as appears in FIGURE 19. Moreover, in passing throughpass 207 the cross-sectional area of the heated clad rod 105a is reducedin the range from about 5% to about 25% dependent upon temperature andthe respective properties of the cladding and core materials in the cladrod. In hot reduction mill 133, metallurgical bonding of the cladding tothe core is obtained. In the case of aluminum powder cladding on aferrous core, such metallurgical bonding appears to achieve somediffusion of aluminum into steel without the production at the interfacebetween those metals of any significant quantity of relatively brittlealuminum-iron compound or of any continuous layer of such compound.Further, there appears to be recrystallization of the original aluminumpowder particles changing grain sizes and boundaries to a significantextent and yielding an adherent non-porous cladding metallurgicallycontinuous and bound to the steel core. Such product is also suitablefor cold wire drawing when the steel core has requisite elongationqualities. Hot reduction mill 133 is also provided with lubricators andscraper blades as in the case of the cladding mill 116 with the furtherprovision that in the case of mills 133 and 136 such lubricaiton may beachieved instead by pumping a stream of water soluble cutting oil intothe entry bite of the rolls 134, or rolls 1387, or both.

Such longitudinal fins as are produced in mill 133 extend from theperiphery of the hot reduced clad rod northeast, southeast, southwestand northwest for a short distance along the parting planes shown inFIGURE 19. Such fins preferably are removed by the fin remover 135mounted on a crossplate 208 secured between and to the Wings 172 so thatthe fin remover 135 surrounds the axis of the metal line along whichclad rod 105a is passing. That fin remover is illustrated in more detailin FIGURES 16 and 17. It comprises two semicircular knives 209 on slideplates which, when clamped together in holder 210 centered in acentering ring 211 around a central opening in plate 208, presentshaving knife edges 212 toward the oncoming hot reduced clad rod whichpasses through a central bore 213 formed by the two knives and anopening 214 in holder 210 as the fins are removed from the periphery ofrod 105a. The sides of the bore 213 diverge slightly in the direction ofmovement of the hot reduced clad rod for relief. The slide plates ofknives 209 are movable in guide slots 215 which maybe centered by theadjustment screws 216. If desired, the tin remover of FIGURES 16 and 17may be utilized to defin the compacted clad rod exiting from mill 116 inplace of the milling cutter fin remover 128.

The definned hot reduced clad rod passes in the illustrated preferredembodiment to the proximate finishing mill 136 where the modified roundproduced by pass 207 is then reshaped by the circular round pass definedby the four Turks-head rolls 137. In mill 136, parts thereofcorresponding generally in structure and functioning to parts of priormills are provided with the same reference numerals with a double accentadded thereto. In finishing mill 136, the frame 169" is rotated aboutthe axis of the metal line and roll pass through an angle of 45 degrees,such frame being secured by bolting to a transverse support plate 136asecured to base 171" and Wings 172". Support brackets 217 secured toplate 136a assist in maintaining frame 169 in precise operativeposition. As shown, the rolls 137 are of somewhat smaller diameter thanthe diameter of the compacting rolls 127 and hot reduction rolls 134.The circular quadrantal groove 218 in rolls 137 has the bottom thereofengaging a respective intercardinal corner of the definned hot reducedclad rod 105a resulting in the finish shaping of that rod to a finishround of the desired end dimension. In the preferred embodiment, noappreciable change is produced in the cross-sectional area of the cladrod as it goes through the pass of the rolls 137. These rolls, moreover,are not driven but receive their movement from the pulling therethroughof the clad rod in the course of the operation. Further, the rolls 137are provided with narrow contacting mating faces 165" in vertical andhorizontal parting planes. Lubrication and scraper blade means areprovided for mill 136 in the same way as they are for mill 133.

The cladding of the finished clad rod 105a is still relatively hot as itleaves the rolls 137. In the case of a cladding made of a softer metallike aluminum, tcmpen atures above about 300 F. offer relatively greateropportunity for deformation or scoring of the cladding. In the preferredembodiment of FIGURES 8 to 21, such a cladding is cooled and maderelatively harder by a longitudinally extending spray pipe 138 suppliedby a communicating pipe 219 with a coolant, such as water 229, sprayedby pipe 138 onto the clad rod 105a issuing from mill 136. A drain trough221 having an outlet 222 is supported between wings 172" on base 171" bya shelf 223 and legs 224 secured thereto. In the case of finishedaluminum clad steel rod, such coolant is evaporated from the surface ofthe rod before the finished clad rod comes in contact with the capstanmechanism 169, thereby promoting traction and control of the tensioningin the metal line by such capstan. Upon leaving the capstan mechanism109, the finished clad rod is coiled as described above ready for use asit is, or for further treatment including wire drawing.

As an example only and without limitation of this invention thereto, thepreferred equipment may be used to make aluminum clad steel core rod ina continuous operation as follows. The starting materials may be coilsof steel rod having a diameter of of an inch and, say, a (3-1043composition, on the one hand, and atomized aluminum powder such as AlcoaNo. 125, on the other hand. In the applicator 121, such cladding powderis applied around the cleaned steel core to increase the over-alldiameter of the core and cladding to about 0.44 of an inch by compactingin the pass of mill 116. The compacted clad rod is pulled along at aspeed of about 30 feet per minute and after having been so compacted anddefinned, it enters induction heater 132 through which it is passed inabout 7 seconds at that speed in the course of which it is heated at theinterface as nearly as can be determined to a temperature between about1050 F. and 1100 F. Immediately following such heating, it is passedthrough the roll pass of hot reduction mill 133 where it is reduced incross section from about 15 to 20%. In the hot reduction mill 133,metallurgical bonding with but scattered traces of aluminum-ironcompound takes place with further densification and apparentrecrystallization of the cladding material. The hot reduced clad rod isthen definned and made into a finish round by mill 136 withoutsignificant change in the cross-sectional area. The finish diameter ofsuch clad red in this example is about 0.4 of an inch with the steelcore diameter being about 0.345 of an inch.

Thus, aluminum clad steel rod can be produced by the equipment of thepreferred embodiment with the core and cladding concentric, with thecore and cladding of desired respective cross-sectional areas andthicknesses, with the cladding continuous, non-porous andmetallurgicaliy bonded over the interface to the core, without anycontinuous layer or detrimental amount of brittle aluminumiron compoundat the interface and with desirable properties of the core and claddingmetals preserved. Further, such new product can be produced continuouslyin the open air without having to take precautions against oxidizing ofthe metals involved and at desirable speeds upwards of twenty-five feetper minute in any length desired. Employment of the principles of thisinvention are utilizable also with respect to cores and claddings ofdifferent selected thicknesses and different selected materialsincluding those, e.g., coating or cladding metals which may have arelatively higher strength than the core metals to be used therewithrespectively. Still further, while the preferred embodiment is but oneoptimum arrangement for economy of labor, materials, equipment andspace, it will be understood that the principles, stages and stepsthereof may be engaged in in somewhat different order, or on a moreextended or contracted basis, or under varying conditions, withoutdeparting from the teachings of our invention set forth herein.

Various other modifications may be made in the dis- 15 closures hereinwithout departure from the spirit of this invention or the scope of theappended claims.

We claim:

1. In a method of cladding a steel rod or wire core with powderedaluminous metal, the steps comprising, in combination, pulling said corecoaxially through an applicator tube, supplying powdered aluminous metalto said tube to fill it around said core substantially until said coreand cladding enter a pass in a set of pressure rolls, roll pressing saidcladding into intimate compaction against the surface of said core insaid pass to a density approaching that of solid metal, heating androlling said pressed clad core at a temperature between about 950 F. andat sufficient pressure and not in excess of about 1180 F. to cause saidcladding to become coherent and to adhere to said core with ametallurgical bond substantially free from compound forming diffusion ofthe respective cladding and core metals into one another at theinterface, and further rolling the clad rod.

2. In a method of cladding a steel rod or wire core with powderedaluminous metal, the steps comprising, in combination, processing saidcore to make it metallurgically clean, pulling said core coaxiallythrough an applicator tube, supplying powdered aluminous metal to saidtube to feed it around said core under a positive force substantiallyuntil said core and cladding enter a compacting pass in a set ofpressure rolls, pressing said cladding into intimate compaction againstthe surface of said core in said pass to density approaching that ofsolid metal, rapidly heating and rolling said pressed clad core at atemperature between 900 F. and 1200 F. and at sufficient pressure tocause said cladding substantially in an unmelted state to becomecoherent and to adhere to said core with a metallurgical bondsubstantially without extensive diffusion of the respective cladding andcore metals into one another at the interface and, further, withoutformation of any substantial, continuous layer of brittle compoundbetween said cladding and core.

3. In a method of cladding a ferrous core with powdered aluminous metal,the steps comprising, in combination, moving said core substantiallylongitudinally through an applicator, positively feeding powderedaluminous metal to said applicator to put said aluminous metal on saidcore, passing said core and cladding through a compacting pass in a setof pressure rolls, directly roll pressing said cladding into intimatecompaction against the surface of said core in said pass to a densityapproach ing that of solid metal, rapidly heating and rolling saidpressed clad core at a temperature in the neighborhood of from about1000 F. to about 1150 F. and at sufficient pressure to cause saidcladding to become coherent and to adhere to said core with ametallurgical bond substantially free from aluminous metal-ironcompound.

4. In a method of cladding a steel rod or wire core with powderedcupreous metal, the steps comprising, in combination, processing saidcore to make it metallurgically clean, pulling said core axially throughan applicator tube, feeding powdered cupreous metal to said tube to fillit around said core substantially until said core and cladding enter apass in a set of pressure rolls, roll pressing said cladding intointimate compaction against the surface of said core in said pass to adensity approaching that of solid metal, rapidly heating and rollingsaid pressed clad core at a temperature between about 1600" F. and notin excess of about 1900 F. and at suflicient pressure to cause saidcladding substantially in an unmelted state to become coherent and toadhere to said core with a metallurgical bond without extensivediffusion of the respective cladding and core metals into one another,and further rolling the clad rod at a lower temperature.

5. In a method of cladding a ferrous core with powdered cupreous metal,the steps comprising, in combination, pulling said core coaxiallythrough an applicator tube, supplying powdered cupreous metal to saidtube to feed it around said core under a positive force, passing saidcore and cladding through a compacting pass in a set of pressure rolls,roll pressing said cladding into intimate compaction against the surfaceof said core in said pass to a density approaching that of solid metal,heating said pressed clad core up to a temperature in the neighborhoodof 1900 F. but below the melting point of said cupreous metal, androlling the clad rod substantially at said temperature sufiicientpressure to effect a reduction in the cross-section of said clad rod andto cause said cladding to become coherent and to adhere to said corewith a metallurgical bond.

6. In a method of cladding a ferrous core with powdered cupreous metal,the steps comprising, in combination, moving said core substantiallylongitudinally through an applicator, feeding powdered cupreous metal tosaid applicator to put said cupreous metal or said core, passing saidcore and cladding through a compacting pass in a set of pressure rolls,roll pressing said cladding into intimate compaction against the surfaceof said core in said pass a density approaching that of solid metal,rapidly heating and rolling said pressed clad core at a temperature inthe neighborhood of about 1900" F. but below the melting point of saidcupreous metal to cause said cladding to become coherent and to adhereto said core with a metallurgical bond.

7. In a method for continuously cladding a metal core in rod or wireform with a cladding metal, initially in powder form, of lower meltingpoint and lower strength which will form a coherent cladding andmetallurgically bond with said core, the steps comprising, incombination, pulling said core continuously at a predetermined speed,feeding an annulus of said cladding metal in powdered form under apositive pressure in the direction of and into contact with said core,radially and simultaneously compacting the cladding metal powder againstsaid core to a substantially uniform thickness around the peripherythereof at sufiicient pressure to densify said cladding metal to a valuewhich approximates the density of the cladding metal in solid form,inductively heating the compacted clad core at least at the interfacebetween said cladding and core metals to a temperature in theneighborhood of but below the melting point of said cladding, radiallyand simultaneously reducing the compacted heated clad core uniformlyaround the periphery thereof relatively soon after said heating atsufficient pressure to effect a reduction in the cross section both ofthe cladding and core metals, cause said cladding to become coherent andmetallurgically bond said cladding and core metals together.

8. In a method for continuously cladding a metal core with a claddingmetal, initially in powder form, of lower melting point and lowerstrength which will form a coherent cladding and a metallurgical bondwith said core, the steps comprising, in combination, moving said corealong a work line at a predetermined speed, feeding said powder metal inthe same direction into engagement with said core to provide a layer ofcladding thereon of predetermined thickness, immediately engaging saidgreen clad core by rolls over the whole surface thereof to compact saidcladding to a density approaching that of the cladding metal in solidform, rapidly heating at least the interface between the core and thecompacted cladding to a temperature in the neighborhood of but below themelting point of the cladding metal, and engaging the compacted cladcore while heated by further rolls exerting a rolling pressuresufficient to cause said cladding to become continuous and coherent andmetallurgically bonded to said core to provide a bimetallic clad coreproduct.

9. In a method of cladding an elongated ferrous member with aluminum,the steps comprising, in combination, cleaning the surface of saidmember to be clad to provide a somewhat roughened surface free offoreign matter, covering said surface with aluminum powder to a desiredthickness, roll pressing said powder and member together uniformly overthe whole surface to make the cladding particles relatively dense andadherent one to the other and form a green clad member, heating at leastthe interface between such cladding and member to a temperature in therange from about 900 F. to a temperature not in excess of 1200" F rollpressing said heated green clad member at sufficient pressure to effecta reduction in the cross section thereof up to a maximum of about 25%and recrystallization in the metallographic structure of said cladding,whereby non-porous aluminum cladding is obtained with metallurgicalbonding thereof to said ferrous member at the interface.

10. In a method of cladding a metallurgically clean ferrous core in rodform with aluminous metal initially in the form of powder particles, thesteps comprising, in combination, pulling said core and said aluminousmetal cladding after application thereto along a straight line, passingsaid core through a larger orifice of predetermined size, feeding saidparticles substantially at atmospheric temperature under a positivepressure in an annulus in the direction of the movement of said coretoward said orifice to engage said core to a substantially uniformthickness and pass therewith through said orifice, passing said particleclad core through a closed roll pass to compact said particlessubstantially :at atmospheric temperature against said core around theentire periphery thereof to a density around the periphery and along thelength thereof approaching the density of said aluminous metal in solidform, rapidly heating said compacted clad rod to a temperature at theinterface in the neighborhood of llO F., passing said compacted clad rodat said temperature through a closed roll pass which is smaller by anamount not less than about than the cross sectional area of saidcompacted clad rod entering said last-mentioned pass, saidabove-mentioned passes being defined by rolls driven at about the speedof said clad rod produced by said firstmentioned pulling, removingoutstanding longitudinal fins from the surface of said clad rod adjacentthe base of said fins respectively as said clad rod issues from each ofthe above-mentioned passes, passing said clad rod through a furtherclosed pass, and relatively rapidly cooling at least said cladding onsaid clad rod.

11. In a method of cladding a metallurgically clean ferrous core in rodform with aluminous metal initially in the form of powder particles, thesteps comprising, in combination, pulling said core and said aluminousmetal cladding after application thereto along a straight line at apredetermined speed, passing said core through a larger orifice ofpredetermined size, feeding said particles under a positive pressure inan annulus in the direction of the movement of said core toward saidorifice to engage said core to a substantially uniform thickness andpass therewith through said orifice, passing said particle clad corethrough a closed roll pass to compact said particles against said corearound the entire periphery thereof to a density around the peripheryand along the length thereof approaching that of solid metal, rapidlyheating said compacted clad rod to a temperature at the interface in theneighborhood of 1000 F. to 1175 F., and passing said heated compactedclad rod through a closed roll pass which is smaller than the crosssectional area of said compacted clad rod entering said last-mentionedpass, said above-mentioned passes being defined by rolls at least somethereof being driven at about said speed.

12. In a continuous method of making an aluminum clad ferrous core rod,the steps comprising, in combination, multiplan-e straightening of saidcore in rod form, metallurgically cleaning the surface of said core byabrasion to provide an unsmooth texture free of foreign matter,concentrically feeding atomized aluminum powder around said core andengaging the same in the bite of power-driven rolls forming a closedgrooved pass slightly smaller than the overall diameter of said enteringpressed powder and core to compact and densify the green cladding onsaid rod, induction heating said compacted green clad rod to atemperature in the neighborhood of 1050* F. to 1150 F. for a period notin excess of ten seconds at a frequency to penetrate through saidcladding and the interface between said cladding and core, promptlyengaging said compacted and heated clad rod in the bite of furtherpowerdriven rolls forming a closed modified shape pass, maintaining alubricant film on contact surfaces of said rolls, said last-mentionedpass being sufficiently smaller in cross section to reduce the crosssection of said clad rod in the neighborhood of from 15% to 20%,removing longitudinal fins respectively as said clad rod emerges fromsaid respective power-driven roll passes, rolling said reduced clad rodto finish shape it, cooling said clad rod leaving said last-mentionedrolling step, and pulling said clad rod in a straight line extending tosaid straightening step.

13. A continuous method of cladding an elongated strength metal corewith a cladding metal initially in powder form having a relatively lowertensile strength and melting point, comprising, in combination, movingthe core longitudinally in a straight line through a cladding metalapplying zone, feeding powder cladding metal in a positive manneragainst said core in said applying zone, roll pressing said claddingmetal against said core into intimate compaction thereagainst to adensity approaching that of said cladding metal in solid metal form,rapidly heating at least the interface between said compacted claddingmetal and core to a temperature approaching the melting point of saidcladding metal without causing the melting of said cladding metal, andsubstantially immediately rolling said heated clad core to provide acontinuous coherent cladding metal layer and a metallurgical bondbetween said cladding metal layer and said core.

14. A continuous method of cladding as set forth in claim 13, in which,said core is ferrous metal, said cladding is aluminous metal, saidheating is induction heating and said temperature is between about 1000F. and about 1180 F. but below the melting point of said aluminousmetal.

15. A continuous method of cladding as set forth in claim 13, in which,said core is ferrous metal, said cladding is cupreous metal, saidheating is induction heating and said temperature is between about 1600"F. and about 1900 F. but below the melting point of said cupreous metal.

16. A bimetallic clad product comprising, in combination, a preformedferrous or alloy core, a cladding comprising a continuous coherent layerof aluminous metal metallurgically bonded to said core, said claddingoriginally comprising powder metal compacted against said core to adensity approaching that of solid metal and remaining substantially inunmeltcd condition throughout rapid heating at a temperature in theneighborhood of from about 1000 F. to about 1150 F. but below themelting point of said aluminous metal and rolling said heated clad coreat sufficient pressure to cause said cladding to become coherent andadhere to said core with a metallurgical bond, the interface betweensaid cladding and core being substantially free of any continuous orsubstantial layer of brittle aluminous metal-iron compound.

17. A bimetallic clad product comprising, in combination, a preformedferrous or alloy core, a cladding com prising a continuous coherentlayer of cupreous metal m-etallurgically bonded to said core, saidcladding originally comprising powder metal compacted against said coreto a density approaching that of solid metal and remaining substantiallyin unmelted condition throughout rapid heating at a temperature betweenabout 1600 F. and a temperature in the neighborhood of about 1900 F. butbelow the melting point of said cupreous metal and rolling said heatedclad core at sufiicient pressure to cause said clad to become coherentand adhere to said core with a metallurgical bond, the interface betweensaid cladding and core being without extensive diffusion of saidcladding UNITED STATES PATENTS Simons June 1, 1943 20 Patterson Nov. 2,Schwarzkopf Mar. 27, Wellman Oct. 12,

Lambert et a] Nov. 22, Findlay et al July 13,

16. A BIMETALLIC CLAD PRODUCT COMPRISING, IN COMBINATION, A PREFORMED FERROUS OR ALLOY CORE, A CLADDING COMPRISING A CONTINUOUS COHERENT LAYER OF ALUMINOUS METAL METALLURGICALLY BONDED TO SAID CORE, SAID CLADDING ORIGINALLY COMPRISING POWDER METAL COMPACTED AGAINST SAID CORE TO A DENSITY APPROACHING THAT OF SOLID METAL AND REMAINING SUBSTANTIALLY IN UNMELTED CONDITION THROUGHTOUT RAPID HEATING AT A TEMPERATURE IN THE NEIGHBORHOOD OF FROM ABOUT 100*F. TO ABOUT 1150*F. BUT BELOW THE MELTING POINT OF SAID ALUMINOUS METAL AND ROLLING SAID HEATED CLAD CORE AT SUFFICIENT PRESSURE TO CAUSE SAID CLADDING TO BECOME COHERENT AD ADHERE TO SAID CORE WITH A METALLURGICAL BOND, THE INTERFACE BETWEEN SAID CLADDING AND CORE BEING SUBSTANTIALLY FREE OF ANY CONTINUOUS OR SUBSTANTIAL LAYER OF BRITTLE ALUMINUOUS METAL-IRON COMPOUND. 